Method and device for producing metal hollow ingots by electroslag remelting

ABSTRACT

A method for producing metal hollow ingots by the electroslag remelting of consumable electrodes in a cooled mould with a circular bottom-plate and a core intended for forming a cavity in the ingot. According to the present invention the core expanding downwards is extracted from the ingot being formed in the direction opposite to that in which the ingot is being built-up. A device for implementing the above method is also disclosed, the said device being characterized in that it is fitted with a core which expands downwards and exceeds in length the ingot being formed.

U United States Patent [1 1 3,687,188 Paton et a1. [45 1 Aug. 29, 1972 [54] METHOD AND DEVICE FOR [581 Field of Search. ..l64/52, 85,136, 252

PRODUCING METAL HOLLOW INGOTS BY ELECTROSLAG [561 CM REMELTING UNITED STATES PATENTS [72] lnventorszBoi-is Evgenievich Paton; Boris 3,610,320 10/1971 Medovar et al.'. ..l64/252 Izrailevich Medovar; Leonty Vasilie- 3,610,319 10/1971 Kleinhagauer ..l64/252 vich Chekotilo; Leonid Viktorovich a Yiktor n gy h I a FOREIGN PATENTS OR APPLICATIONS monov, all of Kiev; Alexander Boris- 859,652 12/1970 Canada ..164/252 ovich Vernik; Leonid Al'exeevich Kamensky, both of Elektrostal; Primary Examiner-J; Spencer Overholser Veniamin Alexandrovich Ishunkin, Assistant m e oh E. Roethel- Moscow; Alexandr Mikhailovich y stem Belenky; Anatoly Ivanovich Shevtsov; Semen Yakovlevich Grinslipon, both [57] ABSTRACT 0f Kulebaki; ,Anamly A method for producing metal hollow ingots by the y fim 9632 19 SPE FQE electroslag remelting of consumable-electrodes in a Dubmsky, Klev; Valery gi cooled mould with a circular bottom-plate and a core P, Kiev; Alexandr Mikhailovich intended for forming a cavity in the ingot. According Toschev,all of USSR. to the present invention the core expanding [73] Assignee: Institut Elektrosvarki ineni E. O. f f extractefi from bemg f Patona akademii Nank vkrainskoi in the direction oppos te to that 111 which the ingot is U S S R being built-up. A device for implementing the above method is also disclosed, the said device being charac- [22] Fled: Apnl 1971 terized in that it is fitted with a core which expands [21] APP]. 131,695 downwards and exceeds in length the ingot being formed.

[52] US. Cl. ..l64/52, 164/136, 164/252 7 Claims, 1 Drawing Figure [51] Int. Cl. ..B22d 27/02 METHOD AND DEVICE FOR PRODUCING METAL HOLLOW INGOTS BY ELECTROSLAG REMELTING The present invention relates to procedures for manufacturing hollow metal ingots and to the devices for accomplishing such procedures.

Known in the prior art is a technique for the production of metal hollow ingots by the electroslag remelting of consumable electrodes in a cooled mould, fitted with a circular bottom-plate and a mandrel, hereinafter referred to as a core, intended for forming a cavity in the ingot. With the above technique the core, mounted with its expanded portion upwards, is removed from the ingot being formed during the melting process by drawing it out in the direction the ingot is being builtup, i.e., upwards. In addition, the layer of metal adjacent to the core is subjected to tensile strain. As a result tears and fissures, originating in the internal surface of the ingot, affect adversely the quality of the ingot obtained. These tears and fissures cannot be removed by subsequent treatment by pressure.

In order to remove these defects the internal surface of the ingots should be subjected to machining which involves the loss of metal, is time-consuming and requires capital expenditures on additional facilities.

It is an object of the present invention to eliminate the above difficulties.

The present invention is, in essence, aimed at providing a process and a device for the production of hollow metal ingots on a more economical basis with the core construction and mode of displacement which allows for enhancement of the ingot quality by precluding the occurrence of fissures on the internal surface of the ingot produced.

The above object is achieved by developing a method for manufacturing tubular metal ingots by the electroslag consumable electrode remelting process in a cooled mould fitted with a circular bottom-plate and a mandrel, hereinafter referred to as a core, designed for the formation of an internal cavity in the ingot, in which method an expanded downwards core is employed in conformity to the present invention. The said core is withdrawn from the ingot, as the latter is being built-up, in the direction opposite to that in which the ingot is growing and at a rate ensuring free shrinkage of the ingot and precluding the possibility of the core to be gripped by the ingot.

The proposed technique is more efficient and assures the production of ingots whose internal surface is free from fissures and, thereby, does not require machining. Freedom from fissures can be attributed to the fact that the metal layer solidifying close to the core is not exposed to tensile stresses. The above procedures enable also the production of ingots with tapered interiors.

It would be sound practice to shift the core downwards, with the mould and the ingot being stationary. A comparatively low-power drive would suffice for that purpose.

The mould together with the ingot enclosed in it, can be shifted upwards, with the core being immobile. Thus, the immersion of the lower portion of the proposed device into the earth below the floor level can be avoided.

The mould and the ingot can be transferred upwards with the core moving at the same time downwards. In

that case it is possible both to decrease the sinking of the lower portion of the device below the floor level (into the earth) and to facilitate handling of the ingot being melted.

To implement the method of the invention a device for the production of metal hollow ingots has been designed, the said device comprising a stand with an electrode holder, consumable electrodes coupled to a power supply, a cooled mould with a circular bottomplate and a cooled core whose function is to form the ingot interior, and the drives to extract the core from the ingot, to transfer the mould and to shift the electrode holder, in which device the core, in conformity to the present invention, expands downwards exceeding in length the ingot being formed.

With the above arrangement the device is simpler in terms of its implementation, more dependable in operation and more convenient in servicing.

The mould may be equipped with a detachable circular bottom and a car for handling the ingot which facilitates both the stripping of the ingot and its transportation.

The core (mandrel) may be connected to the power source. This would enable a more uniform distribution of electric current throughout the slag bath along with the enhancement of the ingot quality.

To make the present invention more clear, below is described an exemplary embodiment of the device for carrying out the proposed procedure in conformity to the invention and with due reference to the drawing, enclosed herewith, which shows elevational view of the above device.

The device for manufacturing metal hollow ingots by the application of the electroslag remelting technique is made up of cooled mould l, fitted with circular bottom-plate 2 and core (mandrel) 3 whose object is to form a cavity in ingot 4. Core 3 widens downwards exceeding in length ingot 4 being formed.

To maintain and to transfer consumable electrodes 5 a stand 6 is provided, being equipped with electrode holder 7 and drive 8 to displace the holder. Consumable electrodes 5 and mould 1 having circular bottomplate 2 are connected to power supply source 9 through leads 10. Core 3 can be also connected to power supply 9. Vertical transfer of core 3 is effected by drive 11. incorporated in the device is drive 12 to achieve vertical displacement of mould 1 together with ingot 4. Where mould l with detachable bottom-plate 2 is used, the device may be fitted with car 13 intended for handling ingot 4.

The device designed to implement the proposed method according to the invention functions as follows:

Core 3, expanded downwards, is fitted tightly from below through circular bottom-plate 2 in mould 1 until there is no clearance between them. The annular space formed by mould 1, bottom-plate 2 and core 3 accommodates consumable electrodes 5 inserted from above. The same annular space is partially charged with a slag whereupon the melting of consumable electrodes 5 is begun according to the conventional operational sequence provided by electroslag remelting technology. During melting both mould l with circular bottomplate 2 and ingot 4, being formed, are stationary.

As ingot 4 is being built-up, core 3, expanding downwards, is lowered at a rate ensuring free shrinkage of hollow ingot 4 and precluding the possibility of the core being gripped by said ingot 4;.

In addition, the compressive forces originating at the point of contact of core and ingot 4 and acting along the ingot axis tend to contract the layer of metal frozen on core 3. Due to the lack of tensile forces acting on ingot 4 at the point of contact with core 3, the incidence of tears, fissures and other defects on the internal surface of the ingot is completely prevented.

In a modified embodiment of the proposed technique mould 1 together with ingot 4 being formed in it, can be shifted upwards at a rate providing for free shrinkage of ingot 4 with core 3 being immovable. lngot 4 being built-up is removed from core 3 by this method.

Core 3 can be extracted from ingot 4 by transferring core 3 down while mould 1 with enclosed ingot 4 is simultaneously moved upwards. It is also possible to displace both mould 1 with ingot 4 and core 3 at one and the same time and in the same direction (upor downwards) but at different rates which would ensure gradual withdrawal of core 3 from ingot 4.

Free shrinkage of ingot 4, being formed, is provided by suitable choice of the taper and rate of travel of core 3. The latter as well as the length of core 3 vary in inverse proportion to its taper.

When the melting process is terminated relative movement of either core 3 or mould 1 containing ingot 4 is allowed to proceed until core 3 is withdrawn from the interior of ingot 4 or until a clearance formed between core 3 and the inner surface of ingot 4 would prevent core 3 from being clamped.

As soon as the core is completely extracted from ingot 4, the latter is extracted from mould l by appropriate handling facilities. Where mould l with detachable bottom-plate 2 is employed, the latter is disconnected from mould l which is preset on car 13 whereupon mould 1 is stripped from ingot 4 with the aid of drive 12 following which ingot 4 together with detachable bottom-plate 2 is carried on car 13 in the required direction.

The proposed procedure and device are applicable for the production of hollow ingots differing in their shape and size, including large-size ingots.

Further advantages of the foregoing device include simple construction, convenient servicing and reliable operation. The method and device can also be useful in producing tubular ingots by other metallurgical procedures.

What is claimed is:

l. A method for producing metal hollow ingots which comprises: feeding slag into a space formed by a cooled mould having a circular bottom-plate and a core which expands downwards and serves for the formation of a cavity in the ingot; electroslag remelting of consumable electrodes to produce an ingot which is builtup in the said space; extracting said core from the ingot in the direction opposite to that in which the ingot is growing, the said extracting being effected as the ingot is being deposited and at a rate ensuring free shrinkage of the ingot and preventing the gripping of said core by the ingot; extracting the core from the ingot on completion of electroslag remelting; and stripping of the ingot.

2. A method, as claimed in claim 1, in which the said core is transferred down and the mould accommodatin%the ingot is stationary.

A method, as claimed in claim 1, m which the said mould together with the ingot is moved upwards with the core remaining stationary.

4. A method, as claimed in claim 1, in which the said mould incorporating the ingot, is shifted upwards and the said core is displaced downwards.

S. A device for producing metal hollow ingots comprising: a stand; an electrode holder slidably mounted on said stand; consumable electrodes attached on the electrode holder; a cooled mould with a circular bottom-plate for forming an ingot by remelting the consumable electrodes; an expanded downwards cooled core inserted in the opening of the circular bottomplate of said cooled mould, the above core exceeding in length the ingot being built-up and designed for forming the ingot interior; a power source connected to the said consumable electrodes and to the cooled mould fitted with the circular bottom-plate; drive means for transferring said electrode holder; second drive means to accomplish vertical travel of the said core; and third drive means for moving said mould with the circular bottom-plate in the vertical direction.

6. A device, as claimed in claim 5, in which the circular bottom-plate of said mould is detachable and a car is provided for handling the the ingot.

7. A device, as claimed in claim 5, in which the said power source is coupled to the above core. 

2. A method, as claimed in claim 1, in which the said core is transferred down and the mould accommodating the ingot is stationary.
 3. A method, as claimed in claim 1, in which the said mould together with the ingot is moved upwards with the core remaining stationary.
 4. A method, as claimed in claim 1, in which the said mould incorporating the ingot, is shifted upwards and the said core is displaced downwards.
 5. A device for producing metal hollow ingots comprising: a stand; an electrode holder slidably mounted on said stand; consumable electrodes attached on the electrode holder; a cooled mould with a circular bottom-plate for forming an ingot by remelting the consumable electrodes; an expanded downwards cooled core inserted in the opening of the circular bottom-plate of said cooled mould, the above core exceeding in length the ingot being built-up and designed for forming the ingot interior; a power source connected to the said consumable electrodes and to the cooled mould fitted with the circular bottom-plate; drive means for transferring said electrode holder; second drive means to accomplish vertical travel of the said core; and third drive means for moving said mould with the circular bottom-plate in the vertical direction.
 6. A device, as claimed in claim 5, in which the circular bottom-plate of said mould is detachable and a car is provided for handling the ingot.
 7. A device, as claimed in claim 5, in which the said power source is coupled to the above core. 